Introduction: Arduino - LCD 1602A I2C - PASSWORD PROTECTED DOOR ACCESS With Relay - KY-019

Picture of Arduino - LCD 1602A I2C - PASSWORD PROTECTED DOOR ACCESS With Relay - KY-019

Hello world! Today i made a simple code to control a electric strike lock with a Password/ Access Code using a 1 channel relay. I don't have such a lock but i demonstrated it with a lamp attached to the relay. Check the next step for the schematic code & Parts list.

(I know! I wrote access wrong in the video..don't mind the

Step 1: Schematic, Code & Parts List

Picture of Schematic, Code & Parts List

You need these following librarys

  • password.h
  • LiquidCrystal_I2C.h
  • Keypad.h

Wire it up like the schematic and it should work after uploading,

if your not seeing anything, try change your I2C Address i will include a Code to scan your address.

You can change this at the line shown below which you can find on line 14 of the code.

  • #define I2C_ADDR 0x27

Most common I2C addresses.

  • PCF8574 = 0x20,
  • PCF8574A = 0x38,
  • PCF8574AT = 0x3F
  • PCF8574T = 0x27

Parts list:

  1. Arduino uno, I used the RobotDyn Uno.
  2. 1 Channel Relay KY-019
  3. Keypad 4x4
  4. LCD 1602 with I2C
  5. Electrical Strike Lock (Not needed to test the code, you will see if relay go's on or off.)

Good luck!


nebloid (author)2016-08-08

Very good. I found that the LiquidCrystal_I2C.h library was causing issues with the functions contained within it. I was able to rectify this by installing the NewliquidCrystal_1.3.4 library which can be found here:

. After that the project worked perfectly. Thanks for the Instructable.

KNEXnCoding (author)2016-05-23

This is cool! I made a much simpler version of this with a 6 character combo with 4 numbers. When I want to take it to the next level, I am going to use this Instructable!

vandenbrande (author)KNEXnCoding2016-05-24

Thanks! it's handy stuff.

AlexAndAmigos (author)2016-05-24


vandenbrande (author)2016-05-23

Follow me for more!

About This Instructable




Bio: Hello world! I make simple & Advanced projects for people who want to learn programming and electronics. Most of my Instructables are about arduino and the ... More »
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